This application is based on and claims the priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 101 11 017.0, filed on Mar. 7, 2001 in Federal Republic of Germany, the entire disclosure of which is incorporated herein by reference.
A power loom has shed forming components such as the heald frames or heald shafts which are operated by electric motors for opening and closing the loom shed in a controlled sequence.
Drive mechanisms for operating the heald shafts of weaving looms which are not so-called shaft looms or so-called eccentric drive looms are known. These known drive mechanisms can be categorized primarily into two categories. One category includes rotational D.C. motor drives. Another category includes so-called linear D.C. motor drives. The first category of the rotational D.C. motor drives includes motors which are operated to repeatedly reverse their rotational direction, for example in an oscillating manner in order to transmit the oscillating reversing motion through so-called detour levers and linkages into an oscillating linear motion of the loom shed forming components.
Further distinctions in the type of drive can be made between so-called direct drives and drives which are connected with the shed forming components through so-called bottom or lower heald frame motions. German Patent Publication DE 196 51 799 A1 discloses such a drive with a lower heald frame motion. Similarly, Japanese Patent Publication JP 07-324247A discloses such a drive with a lower heald frame motion.
Japanese Patent Publication JP 11-124751A discloses a drive for loom shed forming components including a shaft lower heald frame motion wherein the rotational motion of the drive is transmitted to the shaft lower heald frame motion through gear elements and an eccentrically mounted single arm lever. The shaft lower heald frame motion includes a detour lever and a push-pull rod, whereby the rotational motion is converted for each heald shaft into a stroke motion which changes its direction repeatedly.
Japanese Patent Publication JP 11-350285 discloses a drive for the shed forming components of a loom. That drive includes a rotor and a stator of an external armature motor that is electrically controllable. The rotor of such an external armature motor comprises gear teeth around its external circumference. These gear teeth mesh with longitudinal struts of the heald shafts. These struts are formed as toothed racks. No bottom or lower heald frame motions are required for the shed forming components.
The above mentioned German Patent Publication DE 196 51 799 A1 discloses a similar drive as the Japanese Patent Publication JP 11-350285, however in the German disclosure a bottom or lower heald frame motion is required. A disadvantage of that structure is seen in that the loom must be equipped with special shed forming components. More specifically, special heald shafts are required or at the very least, the heald shafts must be provided with elements permitting the coupling of the shafts to the drive as disclosed in German Patent Publication DE 196 51 799 A1. As a result, conventional heald shafts cannot be used and the drive disclosed in the German Patent Publication DE 196 51 799 cannot be used for retrofitting existing looms without substantial changes in the heald shafts, or rather in the coupling portion of the heald shafts.
German Patent Publication DE 198 82 094 A1 discloses an electromagnetic drive mechanism that can be used either for directly or for indirectly driving the heald shafts. When the known mechanism is used as an indirect electromagnetic heald shaft drive, the stroke motion of the heald shafts is accomplished through so-called bottom or lower heald frame motion. When the known electromagnetic drive is acting as a direct drive, motion direction changing means such as detour levers are avoided. The known electromagnetic drive is presumably constructed to include coils and coil cores or armatures. However, no details are disclosed in German Patent Publication DE 198 21 094 A1 for the person of ordinary skill in the art how the advantages mentioned are achieved in fact.
Japanese Patent Publication JP 09-078389A discloses a heald shaft drive without a bottom or lower heald frame motion. The known drive comprises an electric motor generating a rotation motion which is converted into an oscillating linear motion by means of a type of crank drive which transmits the linear motion to the respective heald shaft. Such a drive is also further disclosed in Japanese Patent Publication JP 11-286850.
German Patent Publication DE 198 49 728 A1 discloses a drive falling into the category with a D.C. linear motor as the power portion of the drive mechanism for the shed forming components of the loom. The known drive comprises actuators in the form of circular sectors or quasi-rotation D.C. motors with a common magnetic stator provided for several or all actuators or rather for the magnetic stator flow of several or all actuators. This magnetic stator flow is generated by permanent magnets. Each of these permanent magnets is divided into at least two oppositely polarized sectors and these sectors in turn are mounted in a non-magnetic carrier with a spacing between neighboring permanent magnets. These permanent magnets are spaced from one another by an air gap. A motion transmission element is installed in the air gap. The motion transmission element includes a carrier made of a non-magnetic, electrically non-conducting material. The motion transmission element further includes at least one thin coil. The transmission or transformation of the motion from the motion transmission element to the working or driven element is preferably accomplished by a linking member. A position sensor allocated to each actuator serves as a position pick-up or position indicator. The drive mechanism between the motion transmission member of the linear D.C. motor and the respective shed forming component also requires a special heald shaft or at least suitable modifications for the heald shaft for the interconnection so that the required heald shafts do not correspond to conventional heald shafts and retrofitting is not possible without substantial effort and expense.
The Japanese Patent Publications JP 10-310947A, JP 10-310948A, and JP 10-310949A disclose further linear D.C. motors as drives for the shed forming components of a loom. For each of these conventional drives it is required that special heald shafts are provided since these drives are arranged in the heald frame of the respective heald shaft. The foregoing conventional technical solutions of the problem how to drive heald shafts in a loom have the disadvantage that it is necessary to lift the shaft packet with the armature of the linear D.C. motor out of the loom when it becomes necessary to exchange the heald shaft, for example when the fabric type is to be changed or when shaft repairs are necessary. The reinsertion of the shaft packet into the loom may damage the shaft drives. Another disadvantage is seen in that it is very easy to damage a shaft when the drive motor has a defect since the respective shaft can jam in its guides. Moreover, such conventional drives are suitable only for relatively narrow looms because a center drive having the same drive conception as a drive that is integrated into the shaft side supports or frame side members is not possible.
Another disadvantage of the drive disclosed in Japanese Patent Publication JP 10-310949 A is seen in that either the heald shafts must have different lengths or shafts having the same length relative to one another must be laterally displaced relative to each other in the weaving loom. Such a shaft arrangement does not permit efficiently carrying out the preparations for weaving. Conventional warp thread drawing-in looms must especially be adapted for these conventional drives. Besides, these conventional drives result in relatively wide looms while achieving a comparatively narrow weaving width.
European Patent Publication EP 0,879,990 A2 discloses a drive for the shed forming components of a weaving loom involving a rocker lever system driven by linear motors. This conventional construction has the disadvantage that the position of the shaft connections from shaft to shaft is different. Thus, it is no longer possible to exchange one individual shaft for another which can be a substantial disadvantage, particularly in maintaining a large stock of spare parts.
European Patent Publication EP 0,825,285 A1 discloses an arrangement of shed forming components which are driven by linear motors. Such a conventional construction requires a super structure and a bottom structure for the mounting of the shed forming components. The drive is accomplished in so-called groups of four so that the heald shafts require differently positioned drive connections, more specifically differently positioned shaft couplings. Here again it is more difficult to carry out the preparations for weaving and the coordination of the heald shafts during a shaft exchange is also difficult. Besides, a super structure is known to provide a certain complexity on the weaving floor. The insertion of the heald shafts into the loom as well as their removal from the loom is not without its own problems as compared to other conventional heald shafts.
In view of the foregoing it is the aim of the invention to achieve the following objects singly or in combination:
to provide a drive for loom shed forming components in a loom in such a way that its arrangement in the loom permits the use of conventional heald shafts as shed forming components;
to provide a heald shaft drive capable of cooperating with conventional rapid action couplings or so-called snap locks between the drive and the heald shafts so that conventional bottom heald shaft motions and detour levers between the shafts and the shaft drives are avoided;
to avoid the use of crank drives between the drive power source and the shafts; and
to construct the heald shaft drive in such a manner that it is compatible with any free programming for the drive control to permit different weaves, different weaving pattern repeats, different shaft strokes and different motion profiles of the shafts to be realized, whereby weft yarn parameters should also be taken into account.
According to the invention there is provided a drive mechanism for shed forming components of a loom, said drive mechanism comprising at lest one modular electric motor for each of said shed forming components, said modular electric motor including a stationary motor section, a movable motor section, and a central axis, a motor control electrically connected to said at least one electric motor for oscillating said movable motor section back and forth in opposite motion directions, a push-pull rod, a first articulated coupling operatively connecting a first end of said push-pull rod to said respective shed forming component of said shed forming components, a second articulated coupling operatively connecting a second end of said push-pull rod to said movable motor section radially outwardly of said central axis and a stationary axle adapted for rigid mounting in a frame of said loom, wherein said stationary motor section of said modular electric motor is rigidly secured to said stationary axle as a modular unit.
An important advantage of the heald shaft drive according to the invention is seen in that it permits any desired motion profiles for the heald shafts with regard to the loom shed opening profile and any desired shed closure as well as any desired shaft strokes. The shed closure can be coordinated to color and/or other parameters of the weft threads as well as the type of weave. The avoidance of bottom or lower heald shaft motions results in a shaft drive that reduces costs as well as materials. Moreover, maintenance and repair time savings are achieved, for example when shaft exchanges must be made. Repair and maintenance work is avoided particularly of bearings that are conventionally integrated into detour levers, since such detour levers are avoided according to the invention. A very important further advantage is seen in that all conventional looms can be retrofitted with the shaft drive according to the invention, because conventional loom heald shafts with conventional shaft couplings can be connected directly to the present drives.